rob74 1 day ago

Title: "Astronomers find the edge of the Milky Way"

First sentence in the article: "Astronomers have located the edge of the Milky Way’s star-forming disk for the first time"

Wouldn't you expect someone from a publication called "Sky & Telescope" to know that these two are different things?!

Also, in diagrams showing our galaxy, I would greatly appreciate a "you are here" marker which points out the location of our solar system...

  • thaumasiotes 1 day ago

    > Also, in diagrams showing our galaxy, I would greatly appreciate a "you are here" marker which points out the location of our solar system...

    What would that mean?

    Try locating France on this map: https://en.wikipedia.org/wiki/File:T_and_O_map_Guntherus_Zin...

    • rob74 1 day ago

      Ok, I would be happy with an approximate location too. On that map, I would place France in Europa right beside the mediterraneum, pretty much on the Occidens side (although not at the very edge).

      • thaumasiotes 1 day ago

        Well, to ask you again, what do you think "an approximate location" would mean? How would the labeling be done?

        It's easy enough to take the rob74 position of "I'm going to choose an arbitrary point on this artist's conception and paste a 'you are here' sticker over it", but what would be the point?

        • wvbdmp 23 hours ago

          Well, we’re clearly not in the center, for one thing.

    • kridsdale1 21 hours ago

      It’s right where the V (Latin U) symbol is.

dotancohen 1 day ago

Is this a non-sequiter or just poorly phrased?

  > Disk galaxies like the Milky Way form stars “inside-out” — starting from the center and working outwards through the disk. So, as a general rule, the farther out astronomers look, the younger the stars are.

Do they meant looking out from Earth (which is actually nearer to the center of a spiral arm than to either end) or out from the galactic bulge. Either way doesn't make sense.

  • _factor 1 day ago

    Poorly phrased. The most recent stars are on the edges. The inner stars were first, hence the “working outwards”.

    • kakacik 1 day ago

      But why? Star forms when enough hydrogen (or maybe also helium) clusters together with gravity to spark fusion IIRC. The center of Milky way ain't some ultra dense place where stars are just trillions of kms from each other to support somehow earlier star formation.

      Or did ie dark matter/energy somehow coalesce on the outer edge later? Milky way is supposed to be very old place, almost as old as universe itself so one would expect more homogeneous distribution, at least as a layperson.

      • Ekaros 1 day ago

        You need certain density to start formation progress. Then you get more density as it drags more stuff via gravity from intergalactic void. So new stars form at edges when there is finally enough stuff pulled by gravity of whole galaxy to there for the formation to happen.

        It seems that you need quite large concentrations(as in scale of whole universe average) to actually get to star formation. Otherwise stars would be uniform trough the universe.

        Then again I am not astronomer.

        • addaon 15 hours ago

          > Then you get more density as it drags more stuff via gravity from intergalactic void.

          The pre-stellar cloud has the same mass, and thus the same gravitational impact, as the stars that form from it.

        • dotancohen 4 hours ago

          > You need certain density to start formation progress.

          Aren't fluids (such as a hydrogen gas cloud) densest at the bottom of a gravity well? It would be expected that the nearer one is to the galactic center, the denser the intergalactic medium would be.

  • happytoexplain 1 day ago

    I actually am not following what the ambiguity is - stars farther out from the center are younger, no?

    • kadoban 1 day ago

      The Earth isn't the center of the galaxy, so this feels confusing/confused:

      > So, as a general rule, the farther out astronomers look, the younger the stars are.

      • rafram 1 day ago

        The father out from the center of the galaxy they look, the younger the stars are.

      • jibal 1 day ago

        The location of the Earth is completely irrelevant. "closer" and "farther" refer to the center of the galaxy.

  • malfist 1 day ago

    When does "starting in the center" mean anything besides "starting in the center"?

    The earth is not the center of the galaxy

    • assimpleaspossi 1 day ago

      He didn't say that. He said earth is nearer to the center of a spiral arm.

      • dylan604 1 day ago

        the location of earth has precisely zero to do with the topic

        • assimpleaspossi 1 day ago

          And your reply has zero to do with what I'm talking about.

      • malfist 1 day ago

        What does the center of a spiral arm have to do with the center of the galaxy?

        • assimpleaspossi 1 day ago

          I don't know but that's not what I'm talking about.

    • furyofantares 1 day ago

      The Earth is where the astronomers are. If they are looking outward (away from the center) then the further they look, the younger the stars.

  • JumpCrisscross 1 day ago

    Try: "the farther out [from the center] astronomers look"

  • ww520 1 day ago

    Looking from Earth at the stars closer to the center of a galaxy, they are found to be older. Looking from Earth at the stars closer to the edge of a galaxy, they are found to be younger.

  • eventualcomp 1 day ago

    To use an analogy, to add to everybody else: it's like rings on a tree stump. The innermost part of the stump is the oldest; the outer the youngest. Earth is on one of those in-between rings, neither the oldest nor the newest - doesn't matter which of the in-betweens, to be honest.

    Suppose now that you're an ant on the middle ring of that tree stump. No matter which way you're looking from Earth's middle-ring, either the rings will get gradually older and then younger with increasing distance (if you're looking towards the center-ish), or the rings will get strictly younger (if you're looking away from the center-ish).

    This analogy obviously breaks down if you delve into details but that should give a better intuition to what's going on.

  • furyofantares 1 day ago

    From Earth (where astronomers are) looking "out"ward (away from the bulge).

  • jibal 1 day ago

    Earth isn't relevant. The stars at the center of the galaxy developed first, and development proceeded from the inside out, so the youngest stars are on the edge ... then they get older from there on out, as the stars beyond the edge broke away from the galaxy. The bottom of the age U is the location of the formative edge.

  • two_handfuls 21 hours ago

    They don't mean that the stars migrate out (then further stars would be older), they mean that stars further away from the center start forming later (so further stars are younger).

    I agree that the phrasing can be confusing.

neals 1 day ago

Just the daily post that makes me feel small and insignificant.

  • dylan604 1 day ago

    I prefer that feeling much more than the modern sense from social media where everyone is abnormally important

    • rambojohnson 1 day ago

      Seriously. Being meaningless and insignificant gives you more freedom, and nowhere to hide from what you do with it. I’ve never understood cosmic dread. It feels like a release valve instead of a threat.

chirau 1 day ago

How are claims like these verified?

onchainintel 1 day ago

Incredible. "Hi honey, what did you do at work today? Casually discovered the edge of the galaxy. How are you?"

  • ordu 1 day ago

    I think they have been looking for the edge for years, and the discovery had come gradually over some time. So I don't think that "casually" fits there and "today" doesn't make things better.

yrcyrc 1 day ago

Great. Next Laniakea

TZubiri 1 day ago

Oh thank goodness, I've been looking for that.